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Running constants 
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#1
May714, 05:25 PM

P: 754

Well I am having some difficulty in understanding the running constants... I am not sure if this applies to the Standard Model as well, but I saw that in SUSY recently...
If we take the value of the gaugino masses [itex]m_{\bar{g}},m_{\bar{W}},m_{\bar{B}}[/itex] (by bar I mean Gluino,Wino and Bino) to be equal at some energy scale (~M_{GUT}) then we can go to lower energy scales (let's say at TeV) to find their ratio: [itex]m_{\bar{g}}:m_{\bar{W}}:m_{\bar{B}}≈6:2:1[/itex] I guess this ratio depends on the model. My problem is that I don't understand how we can do that, in the case the SuSy breakdown occurs at lower energies than M_GUT... While SuSy is unbroken, the gauginos will have to be massless, right? If the breakdown occurs at around 2TeV let's say, then it's meaningless to speak about their masses... 


#2
May714, 05:47 PM

P: 227

The same thing happens with fermion masses in the Standard Model. Typically it is just a matter of sloppy wording and what really is running are the Yukawa couplings (at least above EWSB). I am no SUSY expert, but I suspect there is something similar at work here.



#3
May814, 12:28 AM

P: 355




#4
May814, 06:42 AM

P: 754

Running constants
For example do the W and Z bosons we know become massless? I think they do (at least effectively) because you will have energies above the vev energy... 


#5
May814, 08:33 AM

P: 355




#6
May814, 12:56 PM

P: 1,020

Be careful here, it is possible to have a supersymmetric theory of scalars and fermions which does not have gauge interactions. In this case, a supersymmetric multiplet necessarily have the same mass because supercharges commute with the momentum operator, so a supercharge acting on a state does not alter the eigenvalue of p_{μ}p^{μ}.
The equality of masses is a result of presence of auxiliary field which has no kinetic term and eliminating it by EOM yields the constraints on fermion boson masses and coupling constant. 


#7
May1114, 11:07 PM

P: 355

I can't say that I understand what your point is.



#8
May1214, 02:46 AM

P: 1,020




#9
May1214, 05:10 PM

P: 355




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